Various systems are known for supporting loads on roofs, and for installing skylights and/or smoke vents onto, or into, roofs.
A significant motivation for use of skylights is that the daylighting which enters the building through the skylight lenses can reduce or eliminate the need for use of electrical light fixtures during the daylight hours. Further, conventionally-known control systems can monitor the light intensity at desired, selected locations inside the building and automatically turn on selected ones of the electrical light fixtures as needed in order to maintain a desired level of light intensity at the selected locations inside the building, or selectively dim, or turn off, such light fixtures when a desired level of light intensity is being delivered through the skylights.
The benefits of using skylights to obtain daylighting include lower energy costs, less use of fossil fuels for generating electricity, and potentially less worker stress or fatigue. A significant problem associated with use of many conventionally-available skylight lens assemblies is that many conventionally-available skylight lens assemblies are known to have high probability of leaking during rain events.
Commonly used skylighting systems have translucent or transparent covers, also known as lenses, mounted on a support structure, commonly known as a “curb”, which is mounted to building support members inside the building and wherein such support structure extends through an opening in the roof. Ambient daylight passes through the lens and thence through the roof opening and into the building.
Thus, such conventional skylight and smoke vent installations use a curb structure beneath the exterior roofing panels and inside the building enclosure, and extending through the roof structure, in order to provide a support which extends through the roof, past the roof panels, and which supports the skylight lens assembly. Conventional such skylight curbs, thus, are generally in the form of a preassembled box-like structure. Such box-like structure is mounted to building framing members inside the building enclosure, and extends through a respective opening in the roof, and past the respective elongate metal roof panels. Such skylight assembly thus mounts inside the building enclosure, and extends through an opening in a corresponding roof structure. Fitting skylight assemblies into such roof openings presents problems, both for the installer and for the user. A primary problem is that mentioned above, namely that curb-based types of installations of conventional skylight support structures have a tendency to leak water when subjected to rain.
In light of the leakage issues, there is a need for a more effective way to support skylights and smoke vents, thus to bring daylighting into buildings, as well as a more effective way to support a variety of other loads, on roofs.
To achieve desired levels of daylighting, curb-based skylight installations use multiple roof openings spaced regularly about the length and width of a given roof surface through which daylighting is to be received. Each skylight lens is installed over a separate such opening.
In recent developments by the inventors herein, skylight support structures are mounted on the metal roof panels of standing seam roofs, thus to take advantage of the beam strength in the ribs. Various aspects of these developments are disclosed in U.S. Pat. No. 8,438,798 (McLain et al.), U.S. Pat. No. 8,438,799 (McLain et al.), U.S. Pat. No. 8,438,800 (McLain et al.), U.S. Pat. No. 8,438,801 (McLain et al.), U.S. Pat. No. 8,561,364 (Pendley et al.), U.S. Pat. No. 8,567,136 (Pendley et al.), U.S. Pat. No. 8,763,324 (Pendley et al.), U.S. Pat. No. 8,833,009 (Pendley et al.), U.S. Pat. No. 8,844,216 (Pendley et al.), and U.S. Pat. No. 9,441,377 (Pendley et al.), each of which is incorporated herein by reference in its entirety.
In the above patents, the skylight assemblies are raised above elongate panel flats which extend the lengths of the roof panels, whereby rib elements at the sides of adjacent such roof panels are joined to each other in elongate joinders, referred to as the ribs.
The opening for a conventional curb-mounted skylight cuts across multiple such ribs in order to provide a wide enough opening to receive conventionally-available commercial-grade skylight assemblies. Such curb-mounted skylight assembly, itself, includes a curb which is mounted inside the building and extends, from inside the building, through the roof opening and about the perimeter of the opening, thus to support the skylight lens above the flats of the roof panels, as well as above the ribs. Flashing, and conventional pliable tube construction sealants, are applied about the perimeter of the roof opening, between the roof panels and the flashing, including at the cut ribs. Typically, substantially all of such sealant is applied in the panel flats, which means that such sealant is a primary barrier to water leakage about substantially the entire perimeter of the skylight curb.
One of the causes of roof leaks around the perimeter of curb-mounted skylights which attach primarily through the panel flat at the water line is due to foot traffic, such as heel loads or other dynamic loads imposed by workers wheeling gas cylinders or other heavy equipment on the roof panel e.g. with dollies. This type of dynamic loading can cause high levels of stress and/or flexing of the roof panels adjacent the edges of the curb. Such joints between the roof panels and the curb typically rely solely on flashing and tube sealant to provide seals between the curb and the roof panels, most notably in the panel flats. Leaks are also commonly attributed to areas around fastener locations, as the panels flex under load, causing stress between the sealant and the respective curb and/or roof panels; whereby the sealant deforms such that, with repeated flexing of the sealant over time, passages develop through the sealant, which allows for the flow of water through such passages and into the building.
Such curbs, each extending through a separate roof opening, each sealed largely in the panel flats, create multiple opportunities for water to enter the interior of the building. Such opportunities include, without limitation,                (i) the number of individual openings in the roof,        (ii) the tendency of water to collect and stay at the upper end of the curb,        (iii) the disparate expansion and contraction of the roof panels relative to the skylight-supporting curb,        (iv) the lengths of sealed seams in the panel flats, and        (v) flexing of tube sealant pursuant to localized loads being exerted on roof panels adjacent a such skylight or other opening.        
Traditional curb constructions and methods of attachment in most cases thus require that a complex support structure be installed below the metal roof panels and supported from building framing structure, such as purlins, located inside the building enclosure, which allows disparate/discordant movement of the metal roof panels and the skylight assembly relative to each other, as associated with thermal expansion and contraction of the metal roof e.g. in response to differences in temperature changes outside the building relative to contemporaneous temperatures inside the building.
In addition, conventional curb-mounted skylight structures tend to collect condensation on inside surfaces of the heated space in the building.
In the teachings of the above patents, the skylight support assemblies are illustrated as being mounted on adjacent ones of the roof ribs. Insulation from where the skylight opening is cut in the roof is raised up alongside the respective ribs and upstanding support elements of the support structure, in order to provide a thermal break along the sides and ends of the support structure, as well as to attenuate water vapor condensation on inside surfaces of the support structure.
While commercial versions of support structures on roofs based on the above patents have found substantial success in the commercial marketplace, a concession in the commercial versions of such support structures is that such support structures have been produced only in embodiments which span a single roof panel, and are thus limited to less than the 24-inch width of such roof panels.
However, customers for such buildings are familiar with the older style curb-mounted skylights which typically span at least 2 roof panels, and are thus up to about 48 inches wide. While the up to 24-inch wide roof-mounted panels available so far, each 10 feet long, can be mounted end to end over a single roof aperture in order to provide a relatively elongate skylight opening, customers continue to prefer a skylight structure having a nominal width of up to 48 inches.
Thus it would be desirable to provide a roof-mounted load support structure which has the benefits of using the beam strength of the standing seam and the rib, while having a width spanning at least two 24-inch wide roof panels, and which avoids leaks by being mounted on the roof, rather than extending up through the skylight aperture from mountings at the underlying building support structure in the climate controlled space inside the building.
It would further be desirable to provide a roof-mounted load support structure where skylight lenses, spanning at least two 24-inch wide roof panels, can be mounted end to end over a single roof aperture.
It would be still further desirable to provide such a roof-mounted load support structure which directs water, approaching the support structure from up-slope, to panel flats of first and second roof panels on opposing sides of the support structure.